Guy Giorno took over as Mr. Harper’s chief of staff in July, 2008. The Toronto lawyer had served as chief of staff to former Ontario Progressive Conservative Premier Mike Harris and was an architect of his 1995 Common Sense Revolution. Mr. Giorno, who is seen as a hyper-partisan, was the focus of criticism as Mr. Harper’s Conservatives squandered a 10-point lead in the polls through a series of political missteps this summer. In a rare appearance earlier this year, Mr. Giorno was grilled over access-to-information issues and reports of political interference at a House of Commons committee. He is considered one of the country’s leading experts on lobbying registration law.(Adrian Wyld/Adrian Wyld/The Canadian Press)

Ian Brodie became Mr. Harper’s chief of staff after he won a minority government in the 2006 election. Mr. Brodie, who first met Mr. Harper at the University of Calgary in 1990, became involved in the Reform Party and then the merger of the former Progressive Conservative and Alliance parties. A former professor of political science at the University of Western Ontario, he was at the centre of the controversy over a leak of confidential information regarding the North American free-trade agreement, which influenced the Democratic primary race in the United States.(Tom Hanson/Tom Hanson/The Canadian Press)